CAJ | 학술논문

用两相法分离铵态氮(NH4+-N)和硝态氮(NO3--N)培养的水稻苗期叶细胞膜,并测定了细胞膜H+-ATPase水解活性和质子泵活性,以期阐明铵、硝营养对水稻叶细胞膜H+-ATPase的影响.结果表明,叶细胞膜H+-ATPase活性最佳pH值均为6.2.NO3--N培养的水稻叶细胞膜H+-ATPase的水解活性、Vmax和Km均显著高于NH4+-N培养的水稻叶;Western Blot分析结果看出,NO3--N培养的水稻叶细胞膜H+-ATPase酶浓度也高于NH4+-N培养的水稻叶,说明NO3--N培养的水稻叶中单位细胞膜上的H+-ATPase酶分子数量大于NH4+-N培养的水稻叶,这与细胞膜上H+-ATPase蛋白的表达量升高有关.此外,NO3--N培养的水稻叶质子泵初速度和膜囊体内外H+浓度梯度均高于NH4+-N培养.由于NO3-的跨膜运输是与细胞膜上H+-ATPase紧密联系的主动运输过程,NO3--N培养的水稻叶片细胞膜H+-ATPase活性和质子泵活性高可能与水稻叶细胞吸收大量NO3-有关.
용량상법분리안태담(NH4+-N)화초태담(NO3--N)배양적수도묘기협세포막,병측정료세포막H+-ATPase수해활성화질자빙활성,이기천명안、초영양대수도협세포막H+-ATPase적영향.결과표명,협세포막H+-ATPase활성최가pH치균위6.2.NO3--N배양적수도협세포막H+-ATPase적수해활성、Vmax화Km균현저고우NH4+-N배양적수도협;Western Blot분석결과간출,NO3--N배양적수도협세포막H+-ATPase매농도야고우NH4+-N배양적수도협,설명NO3--N배양적수도협중단위세포막상적H+-ATPase매분자수량대우NH4+-N배양적수도협,저여세포막상H+-ATPase단백적표체량승고유관.차외,NO3--N배양적수도협질자빙초속도화막낭체내외H+농도제도균고우NH4+-N배양.유우NO3-적과막운수시여세포막상H+-ATPase긴밀련계적주동운수과정,NO3--N배양적수도협편세포막H+-ATPase활성화질자빙활성고가능여수도협세포흡수대량NO3-유관.
Rice plants (Oryza sativa L. japonica ssp. cv. Nippoabare) were cultivated with ammonium (NH4+-N) or nitrate (NO3--N) as sole nitrogen in a hydroponics experiment, and the plasma membrane vesicles of leaves were isolated by two-phase system at the seedling stage. The plasma membrane H+ -ATPase hydrolytic activity and proton pump activity were analyzed for elucidating the responses of the plasma membrane H+ -ATPase of rice leaves to ammonium or nitrate nu-trition. The purity of plasma membrane is above 80%. The optimum pH for the plasma membrane H+ -ATPase is 6.2 under both NH4+ -N and NO3-N cultivated plants. The plasma membrane H+ -ATPase hydrolytic activity, Vmax and Km obtained from the NO3--N fed rice leaves are significantly higher than those from the NH4+-N fed rice leaves. In addition, the Western Blot showed that the enzyme concentration of plasma membrane H + -ATPase from rice leaves of NO3--N fed plants was higher than that of NH4+ -N fed plants. These results indicate that the higher activity of H+ -ATPase from rice leaves of NO3--N fed Plants is resulted from the increased number of H+ -ATPase units per membrane area and up-regu-lated expression of H+ -ATPase. The H+- pump activity of the plasma membrane from NO3--N fed rice leaves is larger than that of NH4+ -N fed rice leaves. As the NO3- - transport across the plasma membrane is an active transport process in relation to the plasma membrane H+ -ATPase, it might be true that higher activity of plasma membrane H+ -ATPase of rice leaves with NO3- -N nutrition is induced by uptake of large amount NO3- -N in to the leaf cells.